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Armfield - Naval Architecture - NA4 Ships Vibrations Apparatus

The NA4 Ships Vibrations Test Model is designed to enable students to investigate a simple model hull form for resonance phenomena. It may be used in conjunction with the optional Armfield Flotation Tank or any suitable customer supplied tank. Many of the principal phenomena associated with ship resonant vibration are clearly demonstrated. At a more advanced level the distribution of mass and second moment of area may be calculated and using a Young’s Modulus value for the material of the ship shaped beam, the natural frequencies may be estimated by a simple tabular method or other means and compared with the measured value.

Demonstration Capabilities

In air to:

  • Investigate modal characteristics of a simple suspended ship-shaped box girder
  • Produce a resonance curve
  • Produce the amplitude curve of a two-node and three-node flexural model
  • Illustrate the influence of mass and its distribution upon natural flexural frequencies

In water to:

  • Measure the influence of added virtual mass on natural frequency
  • Illustrate the effect of the addition and distribution of sand ballast on the natural frequency
  • Calculate the added virtual mass by different methods and compare with experimentally measured influence using a Schlick-type formula

Key Features

  • Apparatus designed to enable students to investigate a simple model hull form for resonance phenomena
  • The apparatus comprises an experimental model hull, a rigid supporting frame, a vibrator (complete with signal generator and power amplifier) and an optional flotation tank 
  • The experimental model is flat bottomed, wall-sided and open topped. It has an elliptical plan form: 
  • Length to beam ratio 8:1 
  • Length to depth ratio 12:1
  • Used to demonstrate the principle phenomena associated with ship resonant vibration
  • Can be used to investigate resonance phenomena in both air and water
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ArmfieldThe Armfield Industrial Division designs and manufactures research & development systems, primarily for the food, beverage, dairy, edible oil and pharmaceutical industries. Used by many of the world's leading corporations, Armfield systems enable researchers and product developers to replicate full-scale industrial manufacturing processes on a miniature-scale in the laboratory.
[Armfield, Architecture, Naval, NA4, Ships, Vibrations, Apparatus]